Search results
Search for "intramolecular cyclization" in Full Text gives 285 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Synthesis of heterocycles based on azomethine ylides from α-amino acids (or amines) and carbonyl compounds
- Ekaterina V. Berezhnaya,
- Alexander I. Ponyaev,
- Vitali M. Boitsov and
- Alexander V. Stepakov
Beilstein J. Org. Chem. 2026, 22, 705–741, doi:10.3762/bjoc.22.55
Graphical Abstract
Scheme 1: Strategies for the preparation of pyrrolidine derivatives by (3 + 2) cycloaddition of azomethine yl...
Scheme 2: (3 + 2) Cycloaddition of iminoesters to dimethylmaleate.
Scheme 3: Cycloaddition of 1 with various dipolarophiles catalyzed by Ag(I)-L1.
Scheme 4: Cycloaddition of 1 with tert-butyl acrylate catalyzed by Ag(I)-L2.
Scheme 5: Cycloaddition of 1 with dimethyl maleate catalyzed by Cu(I)-L3.
Scheme 6: Cycloaddition of 1 with alkenes catalyzed by Zn(II)-t-Bu-BOX (L4).
Scheme 7: (3 + 2) Cycloaddition of iminoesters to acrylates.
Scheme 8: Catalytic double (3 + 2) cycloaddition to form pyrrolizidine derivatives.
Scheme 9: (3 + 2) Cycloaddition of iminoethers to vinyl phenyl sulfone.
Scheme 10: Regiodivergent and enantioselective synthesis of pyrrolidines 16 and 17.
Scheme 11: Substrate-controlled regioreversible "normal" and "incomplete" 1,3-dipolar cycloaddition.
Scheme 12: Enantioselective synthesis of exo-/endo-pyrrolidines.
Scheme 13: (3 + 2) Cycloaddition of iminoethers 21 to dipolarophiles 22–24.
Scheme 14: Synthesis of bicyclic pyrrolidines 29 from cyclopentene-1,3-diones.
Scheme 15: (3 + 2) Cycloaddition of aldimine esters and allyl alcohols using copper-ruthenium catalysis.
Scheme 16: Synthesis of 3,3-difluoro- and 3,3,4-trifluoropyrrolidine derivatives.
Scheme 17: Use of iminoesters from natural compounds and pharmaceuticals for reactions with 1,1-difluoro- and ...
Scheme 18: Reaction of iminoesters with 1,3-enynes.
Scheme 19: Synthesis of pyrrolidines from iminoesters and vinyl(hetero)arenes.
Scheme 20: Synthesis of exo-pyrrolidines 42 and 43.
Scheme 21: Enantioselective synthesis of heteroarylpyrrolidines 45 and 46.
Scheme 22: Catalytic reaction of (3 + 2) cycloaddition of imines 12 to benzofulvenes 47.
Scheme 23: Fullerene as a dipolarophile in (3 + 2) cycloaddition reactions.
Scheme 24: Asymmetric synthesis of optically active tetrasubstituted pyrrolidines 54.
Scheme 25: (3 + 2) Cycloaddition reaction of imines 55 and α,β-unsaturated aldehydes.
Scheme 26: Probable mechanism of enantioselective (3 + 2) cycloaddition of azomethine ylides to α,β-unsaturate...
Scheme 27: Cycloaddition between iminoesters 12 and sulfinylimines 58.
Scheme 28: (3 + 2) Cycloaddition between triarylideneacetylacetone and azomethine ylides in the presence of ti...
Scheme 29: Stereoselective synthesis of decahydropyrrolo[2,1,5-cd]indolizine 66.
Scheme 30: Synthesis of policyclic derivatives 71 and 72.
Scheme 31: Catalytic аsymmetric (3 + 2) сycloaddition of 2-pyridylimines with N-methylmaleimide.
Scheme 32: Catalytic аsymmetric (3 + 2) сycloaddition of 2-pyridylimines 1 with other dipolarophiles.
Scheme 33: Enantioselective (3 + 2) cycloaddition of silylimine with various dipolarophiles.
Scheme 34: Proposed mechanism of formation of pyrrolidines 78.
Scheme 35: Synthesis of polyheterocyclic pyrrolidines 82–91.
Scheme 36: Synthesis of spirocyclic (95) and fused (96) pyrrolidines.
Scheme 37: (3 + 2) Cycloaddition involving aromatic aldehydes 97, N-propargylmaleimide (98) and α-amino acids ...
Scheme 38: Synthesis of pyrrolizidines 106 and by-product 107.
Scheme 39: Iridium-catalyzed three-component cascade (3 + 2) cycloaddition.
Scheme 40: Intramolecular (3 + 2) cycloaddition of N-alkenylpyrrole-2-carbaldehyde 110 and α-amino acids.
Scheme 41: Three-component (3 + 2) cycloaddition involving fullerene.
Scheme 42: Four-component stereoselective one-pot synthesis of spiro-cycloadducts 119–122.
Scheme 43: Reactions of azomethine ylide 123 with cyclopropenes.
Scheme 44: Three-component reactions involving ninhydrin, cyclopropenes and acyclic α-amino acids.
Scheme 45: Reaction of cyclopropenes 138 with the N-protonated form of Ruhemann purple 137.
Scheme 46: Enantioselective (3 + 2) cycloaddition of azomethine ylides generated in situ from isatins and amin...
Scheme 47: (3 + 2) Cycloaddition of cyclohexenone 143, isatins 140 and aminomalonic diesters 141, catalyzed by...
Scheme 48: Enantioselective (3 + 2) cycloaddition of azomethine ylides generated in situ from isatins and amin...
Scheme 49: Enantioselective (3 + 2) cycloaddition of azomethine ylides generated in situ from isatins and benz...
Scheme 50: (3 + 2) Cycloaddition involving isatins, azetidine-2-carboxylic acid, maleimides or itaconimides.
Scheme 51: (3 + 2) Cycloaddition involving isatins, amino acids and tetraethylvinylidenebis(phosphonate).
Scheme 52: Synthesis of spirooxindoles 156 from triarylideneacetylacetones 155.
Scheme 53: Synthesis of spirooxindole derivatives 157–160.
Scheme 54: Synthesis of hybrid spiro-heterocycles 164–166.
Scheme 55: Formation of azomethine ylide from isatin and sarcosine.
Scheme 56: (3 + 2) Cycloaddition involving isatins, amino acids and trans-3-benzoylacrylic acid.
Scheme 57: Regioselective synthesis of spirooxindoles 170.
Scheme 58: Synthesis of hybrid spiro-heterocycles 86.
Scheme 59: (3 + 2) Cycloaddition involving acenaphthenequinones, amino acids and cyclopropenes.
Scheme 60: Synthesis of hybrid glyco-3-nitrochromane cycloadducts 179.
Scheme 61: Synthesis of spiro[indenoquinoxaline-(thia)pyrrolizidines] 90a.
Scheme 62: Three-component reactions of cyclopropenes, 11H-indeno[1,2-b]quinoxalin-11-onesand α-amino acids, s...
Scheme 63: Synthesis of hybrid glyco-3-nitrochromane cycloadducts 92.
Scheme 64: (3 + 2) Cycloaddition of 11H-benzo[4,5]imidazo[1,2-a]indol-11-one (189) with cyclopropenes and male...
Scheme 65: Diastereoselective synthesis of spiro derivatives of barbituric acid from alloxan 193, α-amino acid...
Scheme 66: Probable mechanism of formation of azomethine ylide from alloxan and ʟ-proline.
Scheme 67: Three-component reactions involving tryptanthrin 196, α-amino acids and cyclopropenes.
Spirobarbiturates with a pyrrolizidine moiety: synthesis, structure and biological evaluation
- Arthur A. Puzyrkov,
- Andrew S. Drachuk,
- Ekaterina A. Popova,
- Alexander V. Stepakov and
- Vitali M. Boitsov
Beilstein J. Org. Chem. 2026, 22, 274–288, doi:10.3762/bjoc.22.20
- by intramolecular cyclization to yield a lactone, which undergoes decarboxylation to produce the corresponding azomethine ylide. In our system, we propose this generated ylide reacts with N-substituted maleimides 3a–p such that the transformation predominantly proceeds via the endo-TS, leading to
Graphical Abstract
Scheme 1: Biologically active compounds with a spirobarbiturate moiety in their structure [7-12].
Scheme 2: Biologically active alkaloids with a pyrrolizidine moiety.
Scheme 3: Previous studies on the three-component synthesis of spirobarbiturates.
Scheme 4: Synthesis of racemic spirobarbiturates 4a–p via one-pot three-component reaction of alloxan (1), ʟ-...
Scheme 5: A plausible mechanism of spirobarbiturate formation from alloxan (1), ʟ-proline (2), and N-substitu...
Figure 1: Schematic structures of endo- and exo-adducts of spirobarbiturates 4.
Figure 2: X-ray crystal structures of compounds 4b (CCDC 2391172, left) and 4c (CCDC 2391171, right).
Figure 3: Unit cell packing of products 4b (left) and 4c (right).
Figure 4: HS mapped with dnorm for compounds 4b (left) and 4c (right).
Figure 5: A segment of the crystal structure of compound 4b with the HS (dnorm), showing intermolecular conta...
Figure 6: A segment of the crystal structure of compound 4c with the HS (dnorm), showing intermolecular conta...
Figure 7: Microscopic images of treated cells and state of the actin cytoskeleton of Sk-mel-2 cells after cul...
Figure 8: Docked view of compounds 4f, 4g, 4i, 4k, and 4l with the target protein (PDB ID: 8DNH).
Total synthesis of natural products based on hydrogenation of aromatic rings
- Haoxiang Wu and
- Xiangbing Qi
Beilstein J. Org. Chem. 2026, 22, 88–122, doi:10.3762/bjoc.22.4
- addition to indirectly reduce the heteroaromatic ring of the isoquinoline to yield compound 118. This was followed by desilylation with TBAF and spontaneous intramolecular cyclization to yield the tricyclic 119. With 119 in hand, the double bond was diastereoselectively hydrogenated using Et3SiH and TFA
- mechanistic hypothesis. Based on this stereochemical control, the Stoltz team successfully obtained the asymmetric hydrogenation product 176, which spontaneously underwent intramolecular cyclization to furnish the bridged cyclic compound 177. With compound 177 in hand, a series of three transformations
- through sequential nucleophilic attack and intramolecular cyclization. (+)-Isomatrine was subsequently synthesized through catalytic hydrogenation via Rh/C, LAH reduction, and tertiary amine oxidation (Scheme 28). After synthesizing (+)-isomatrine, the effects of catalyst type, loading, temperature, and
Graphical Abstract
Scheme 1: The association between dearomatization and natural product synthesis.
Scheme 2: Key challenges in hydrogenation of aromatic rings.
Scheme 3: Hydrogenation of heterocyclic aromatic rings.
Scheme 4: Hydrogenation of the carbocyclic aromatic rings.
Scheme 5: Hydrogenation of the heterocycle part in bicyclic aromatic rings.
Scheme 6: Hydrogenation of the heterocycle part in bicyclic aromatic rings.
Scheme 7: Hydrogenation of benzofuran, indole, and their analogues.
Scheme 8: Hydrogenation of benzofuran, indole, and their analogues.
Scheme 9: Total synthesis of (±)-keramaphidin B by Baldwin and co-workers.
Scheme 10: Total synthesis of (±)-LSD by Vollhardt and co-workers.
Scheme 11: Total synthesis of (±)-dihydrolysergic acid by Boger and co-workers.
Scheme 12: Total synthesis of (±)-lysergic acid by Smith and co-workers.
Scheme 13: Hydrogenation of (−)-tabersonine to (−)-decahydrotabersonine by Catherine Dacquet and co-workers.
Scheme 14: Total synthesis of (±)-nominine by Natsume and co-workers.
Scheme 15: Total synthesis of (+)-nominine by Gin and co-workers.
Scheme 16: Total synthesis of (±)-lemonomycinone and (±)-renieramycin by Magnus.
Scheme 17: Total synthesis of GB13 by Sarpong and co-workers.
Scheme 18: Total synthesis of GB13 by Shenvi and co-workers.
Scheme 19: Total synthesis of (±)-corynoxine and (±)-corynoxine B by Xia and co-workers.
Scheme 20: Total synthesis of (+)-serratezomine E and the putative structure of huperzine N by Bonjoch and co-...
Scheme 21: Total synthesis of (±)-serralongamine A and the revised structure of huperzine N and N-epi-huperzin...
Scheme 22: Early attempts to indenopiperidine core.
Scheme 23: Homogeneous hydrogenation and completion of the synthesis.
Scheme 24: Total synthesis of jorunnamycin A and jorumycin by Stoltz and co-workers.
Scheme 25: Early attempt towards (−)-finerenone by Aggarwal and co-workers.
Scheme 26: Enantioselective synthesis towards (−)-finerenone.
Scheme 27: Total synthesis of (+)-N-methylaspidospermidine by Smith, Grigolo and co-workers.
Scheme 28: Dearomatization approach towards matrine-type alkaloids.
Scheme 29: Asymmetric total synthesis to (−)-senepodine F via an asymmetric hydrogenation of pyridine.
Scheme 30: Selective hydrogenation of indole derivatives and application.
Scheme 31: Synthetic approaches to the oxindole alkaloids by Qi and co-workers.
Scheme 32: Total synthesis of annotinolide B by Smith and co-workers.
Synthesis and applications of alkenyl chlorides (vinyl chlorides): a review
- Daniel S. Müller
Beilstein J. Org. Chem. 2026, 22, 1–63, doi:10.3762/bjoc.22.1
- systems, with no successful extension to other ring sizes. The proposed mechanism involves initial generation of a tertiary or benzylic carbocation, followed by intramolecular cyclization with a pendant alkyne to furnish a vinyl cation intermediate. This species is postulated to be trapped by the solvent
Graphical Abstract
Figure 1: Representative alkenyl chloride motifs in natural products. References: Pinnaic acid [8], haterumalide ...
Figure 2: Representative alkenyl chloride motifs in pharmaceuticals and pesticides. References: clomifene [25], e...
Figure 3: Graphical overview of previously published reviews addressing the synthesis of alkenyl chlorides.
Figure 4: Classification of synthetic approaches to alkenyl chlorides.
Scheme 1: Early works by Friedel, Henry, and Favorsky.
Scheme 2: Product distribution obtained by H NMR integration of crude compound as observed by Kagan and co-wo...
Scheme 3: Side reactions observed for the reaction of 14 with PCl5.
Scheme 4: Only compounds 15 and 18 were observed in the presence of Hünig’s base.
Scheme 5: Efficient synthesis of dichloride 15 at low temperatures.
Scheme 6: Various syntheses of alkenyl chlorides on larger scale.
Scheme 7: Scope of the reaction of ketones with PCl5 in boiling cyclohexane.
Scheme 8: Side reactions occur when using excess amounts of PCl5.
Scheme 9: Formation of versatile β-chlorovinyl ketones.
Scheme 10: Mixture of PCl5 and PCl3 used for the synthesis of 49.
Scheme 11: Catechol–PCl3 reagents for the synthesis of alkenyl chlorides.
Scheme 12: (PhO)3P–halogen-based reagents for the synthesis of alkenyl halides.
Scheme 13: Preparation of alkenyl chlorides from alkenyl phosphates.
Scheme 14: Preparation of alkenyl chlorides by treatment of ketones with the Vilsmeier reagent.
Scheme 15: Preparation of electron-rich alkenyl chlorides by treatment of ketones with the Vilsmeier reagent.
Scheme 16: Cu-promoted synthesis of alkenyl chlorides from ketones and POCl3.
Figure 5: GC yield of 9 depending on time and reaction temperature.
Figure 6: Broken reaction flask after attempts to clean the polymerized residue.
Figure 7: GC yield of 9 depending on the amount of CuCl and time.
Scheme 17: Treatment of 4-chromanones with PCl3.
Scheme 18: Synthesis of alkenyl chlorides from the reaction of ketones with acyl chlorides.
Scheme 19: ZnCl2-promoted alkenyl chloride synthesis.
Scheme 20: Regeneration of acid chlorides by triphosgene.
Scheme 21: Alkenyl chlorides from ketones and triphosgene.
Scheme 22: Various substitution reactions.
Scheme 23: Vinylic Finkelstein reactions reported by Evano and co-workers.
Scheme 24: Challenge of selective monohydrochlorination of alkynes.
Scheme 25: Sterically encumbered internal alkynes furnish the hydrochlorination products in high yield.
Scheme 26: Recent work by Kropp with HCl absorbed on alumina.
Scheme 27: High selectivities for monhydrochlorination with nitromethane/acetic acid as solvent.
Figure 8: Functionalized alkynes which typically afford the monhydrochlorinated products.
Scheme 28: Related chorosulfonylation and chloroamination reactions.
Scheme 29: Reaction of organometallic reagents with chlorine electrophiles.
Scheme 30: Elimination reactions of dichlorides to furnish alkenyl chlorides.
Scheme 31: Elimination reactions of allyl chloride 182 to furnish alkenyl chloride 183.
Scheme 32: Detailed studies by Schlosser on the elimination of dichloro compounds.
Scheme 33: Stereoselective variation caused by change of solvent.
Scheme 34: Elimination of gem-dichloride 189 to afford alkene 190.
Scheme 35: Oxidation of enones to dichlorides and in situ elimination thereof.
Scheme 36: Oxidation of allylic alcohols to dichlorides and in situ elimination thereof.
Scheme 37: Chlorination of styrenes with SOCl2 and elimination thereof.
Scheme 38: Chlorination of styrenes with SOCl2 and elimination thereof.
Scheme 39: Fluorine–chlorine exchange followed by elimination.
Scheme 40: Intercepting cations with alkynes and trapping of the alkenyl cation intermediate with chloride.
Scheme 41: Investigations by Mayr and co-workers.
Scheme 42: In situ activation of benzyl alcohol 230 with BCl3.
Scheme 43: In situ activation of benzylic alcohols with TiCl4.
Scheme 44: In situ activation of benzylic alcohols with FeCl3.
Scheme 45: In situ activation of benzylic alcohols with FeCl3.
Scheme 46: In situ activation of aliphatic chlorides and alcohols with ZnCl2, InCl3, and FeCl3.
Scheme 47: In situ generation of benzylic cations and trapping thereof with alkynes.
Scheme 48: Intramolecular trapping reactions affording alkenyl halides.
Scheme 49: Intramolecular trapping reactions affording alkenyl chlorides.
Scheme 50: Intramolecular trapping reactions of oxonium and iminium ions affording alkenyl chlorides.
Scheme 51: Palladium and nickel-catalyzed coupling reactions to afford alkenyl chlorides.
Scheme 52: Rhodium-catalyzed couplings of 1,2-trans-dichloroethene with arylboronic esters.
Scheme 53: First report on monoselective coupling reactions for 1,1-dichloroalkenes.
Scheme 54: Negishi’s and Barluenga’s contributions.
Scheme 55: First mechanistic investigation by Johnson and co-workers.
Scheme 56: First successful cross-metathesis with choroalkene 260.
Scheme 57: Subsequent studies by Johnson.
Scheme 58: Hoveyda and Schrock’s work on stereoretentive cross-metathesis with molybdenum-based catalysts.
Scheme 59: Related work with (Z)-dichloroethene.
Scheme 60: Further ligand refinement and traceless protection of functional groups with HBpin.
Scheme 61: Alkenyl chloride synthesis by Wittig reaction.
Scheme 62: Alkenyl chloride synthesis by Julia olefination.
Scheme 63: Alkenyl chloride synthesis by reaction of ketones with Mg/TiCl4 mixture.
Scheme 64: Frequently used allylic substitution reactions which lead to alkenyl chlorides.
Scheme 65: Enantioselective allylic substitutions.
Scheme 66: Synthesis of alkenyl chlorides bearing an electron-withdrawing group.
Scheme 67: Synthesis of α-nitroalkenyl chlorides from aldehydes.
Scheme 68: Synthesis of alkenyl chlorides via elimination of an in situ generated geminal dihalide.
Scheme 69: Carbenoid approach reported by Pace.
Scheme 70: Carbenoid approach reported by Pace.
Scheme 71: Ring opening of cyclopropenes in the presence of MgCl2.
Scheme 72: Electrophilic chlorination of alkenyl MIDA boronates to Z- or E-alkenyl chlorides.
Scheme 73: Hydroalumination and hydroboration of alkynyl chlorides.
Scheme 74: Carbolithiation of chloroalkynes.
Scheme 75: Chlorination of enamine 420.
Scheme 76: Alkyne synthesis by elimination of alkenyl chlorides.
Scheme 77: Reductive lithiation of akenyl chlorides.
Scheme 78: Reactions of alkenyl chlorides with organolithium reagents.
Scheme 79: Reactions of alkenyl chlorides with organolithium reagents.
Scheme 80: Addition–elimination reaction of alkenyl chloride 9 with organolithium reagents.
Scheme 81: C–H insertions of lithiumcarbenoids.
Scheme 82: Pd-catalyzed coupling reactions with alkenyl chlorides as coupling partner.
Scheme 83: Ni-catalyzed coupling of alkenylcopper reagent with alkenyl chloride 183.
Scheme 84: Ni-catalyzed coupling of heterocycle 472 with alkenyl chloride 473.
Scheme 85: Synthesis of α-chloroketones by oxidation of alkenyl chlorides.
Scheme 86: Tetrahalogenoferrate(III)-promoted oxidation of alkenyl chlorides.
Scheme 87: Chlorine–deuterium exchange promoted by a palladium catalyst.
Scheme 88: Reaction of alkenyl chlorides with thiols in the presence of AIBN (azobisisobutyronitrile).
Scheme 89: Chloroalkene annulation.
Competitive cyclization of ethyl trifluoroacetoacetate and methyl ketones with 1,3-diamino-2-propanol into hydrogenated oxazolo- and pyrimido-condensed pyridones
- Svetlana O. Kushch,
- Marina V. Goryaeva,
- Yanina V. Burgart,
- Marina A. Ezhikova,
- Mikhail I. Kodess,
- Pavel A. Slepukhin,
- Alexandrina S. Volobueva,
- Vladimir V. Zarubaev and
- Victor I. Saloutin
Beilstein J. Org. Chem. 2025, 21, 2716–2729, doi:10.3762/bjoc.21.209
- compositions of antitumor antibiotics of the kigamycin family include the oxazolo[3,2-a]pyridine skeleton [55][56]. To obtain oxazolopyridones containing trifluoromethyl substituents, the syntheses have been proposed, which are based on the intramolecular cyclization of 1-phenyl-2-(4-(trifluoromethyl)piperidin
- at the acyl moiety with the amino group of diamino alcohol 3 to generate a three-component intermediate B (Scheme 4). The latter undergoes intramolecular cyclization involving the C=N bond in two equally probable directions: by adding a free amino group to form a hexahydropyrimidine ring of
- intermediate C (path a), or by adding an OH group to generate an oxazolidine ring of intermediate D (path b). The subsequent intramolecular cyclization of intermediates C and D involving a secondary NH group and an ester substituent yields the bicycles 4 and 5, respectively (Scheme 4). In the reactions with
Graphical Abstract
Figure 1: Structures of bioactive molecules with trifluoromethylpyridine and piperidine frameworks.
Scheme 1: The reaction of ethyl trifluoroacetoacetate (1), acetone (2a) and 1,3- diaminopropan-2-ol (3).
Scheme 2: Three-component reaction of ethyl trifluoroacetoacetate (1), alkyl methyl ketones 2b,c and 1,3-diam...
Scheme 3: Three-component reaction of ethyl trifluoroacetoacetate (1), acetophenone (2d) and 1,3-diaminopropa...
Scheme 4: The proposed mechanism of three-component cyclization of 3-oxo ester 1, methyl ketones 2a–d and 1,3...
Figure 2: ORTEP view of compounds 4асc (a, CCDC: 2479553), 4аct (b, CCDC: 2479554), 4аtt (c, CCDC: 2479555), ...
Figure 3: ORTEP view of compound 5ctc (a, CCDC: 2479558), 5ctt (b, CCDC: 2479559) showing with the thermal el...
Figure 4: The fragments of the 1H NMR spectra (400 MHz, DMSO-d6) of diastereomers 4acc (a), 4аct (b), 4аtt (c...
Figure 5: Fragments of 1H NMR spectra (400 MHz, DMSO-d6) of hexahydrooxazolo[3,2-a]pyridin-5-ones 5ctc (a) an...
Tandem hydrothiocyanation/cyclization of CF3-iminopropargyl alcohols with NaSCN in the presence of AcOH
- Ruslan S. Shulgin,
- Ol’ga G. Volostnykh,
- Anton V. Stepanov,
- Igor’ A. Ushakov,
- Alexander V. Vashchenko and
- Olesya A. Shemyakina
Beilstein J. Org. Chem. 2025, 21, 2694–2702, doi:10.3762/bjoc.21.207
- , thioethers, disulfides, phosphonothioates, and trifluoromethyl sulfides. Additionally, due to the presence of two electrophilic sites (the sulfur atom and the carbon of the nitrile function), thiocyanates can readily undergo domino-type intramolecular cyclization reactions to form heterocycles. So, if a
- dihydrofurans 3d,e remained comparable to those of 3a,b. Perhaps the yields of salts 2d,e were affected by steric factors hindering the intramolecular cyclization or their stability under the reaction conditions. Using TMS-protected secondary and primary iminopropargyl alcohols 1f,g (due to their instability
Graphical Abstract
Scheme 1: Examples of hydrothiocyanation/cyclization of alkynes.
Figure 1: 1H and 19F NMR monitoring of 1a/NaSCN/AcOH (a, b) and 1g/NaSCN/AcOH (c, d) reaction mixtures in MeC...
Scheme 2: Plausible reaction mechanism.
Scheme 3: Oxidation of isothiazolium thiocyanate 2a.
An Fe(II)-catalyzed synthesis of spiro[indoline-3,2'-pyrrolidine] derivatives
- Elizaveta V. Gradova,
- Nikita A. Ozhegov,
- Roman O. Shcherbakov,
- Alexander G. Tkachenko,
- Larisa Y. Nesterova,
- Elena Y. Mendogralo and
- Maxim G. Uchuskin
Beilstein J. Org. Chem. 2025, 21, 2383–2388, doi:10.3762/bjoc.21.183
- bond cleavage to generate an N-imidoyl radical intermediate that undergoes intramolecular cyclization to yield the spirocyclic product (Scheme 1, path g) [14]. Notably, iron is known to exhibit similar behavior in single-electron transfer (SET) processes [15][16][17]. In fact, we previously
Graphical Abstract
Figure 1: Natural and synthetic bioactive spiro[indoline-3,2'-pyrrolidine] derivatives.
Scheme 1: Previous approaches and our work.
Scheme 2: The reaction of 2-arylindoles 1 with α,β-unsaturated ketones 2. aIsolated yield of the 5 mmol scale...
Scheme 3: The scope of the Fe-catalyzed spirocyclization. aIsolated yield of the 4.2 mmol scale experiment.
Scheme 4: The proposed mechanism of product 4 formation.
Comparative analysis of complanadine A total syntheses
- Reem Al-Ahmad and
- Mingji Dai
Beilstein J. Org. Chem. 2025, 21, 2334–2344, doi:10.3762/bjoc.21.178
- intramolecular cyclization to afford alkyne–nitrile 19 for the first [2 + 2 + 2] cycloaddition with bis(trimethylsilyl)butadiyne (20). This transformation proceeded smoothly under thermal conditions with CpCo(CO)2 to afford 21 as the major regioisomer (rr = 25:1) [22]. Removal of the two TMS groups and
Graphical Abstract
Scheme 1: Complanadine natural products and their plausible biosynthesis.
Scheme 2: The Siegel total synthesis of complanadine A enabled by [2 + 2 + 2] cycloadditions.
Scheme 3: The Sarpong total synthesis of complanadine A enabled by a biomimetic strategy and C–H activation.
Scheme 4: The Tsukano total synthesis of complanadine A enabled by Diels–Alder cycloaddition, Heck cyclizatio...
Scheme 5: The Dai total synthesis of complanadine A using single-atom skeletal editing.
Scheme 6: Comparative summary of the four complanadine A total syntheses.
Enantioselective radical chemistry: a bright future ahead
- Anna C. Renner,
- Sagar S. Thorat,
- Hariharaputhiran Subramanian and
- Mukund P. Sibi
Beilstein J. Org. Chem. 2025, 21, 2283–2296, doi:10.3762/bjoc.21.174
- radical reaction and can occur either intermolecularly or as an intramolecular cyclization reaction. Radical coupling or combination is a possible transformation that is more feasible when one of the radicals is relatively stabilized (a persistent radical). Trapping a radical with a transition metal is
Graphical Abstract
Figure 1: Methods of radical generation (A) and general types of radical reactions (B).
Figure 2: Chiral catalysis in enantioselective radical chemistry [13-37].
Scheme 1: Diastereo- and enantioselective additions of nucleophilic radicals to N-enoyloxazolidinone and pyrr...
Scheme 2: Organocatalyzed formal [3 + 2] cycloadditions affording substituted pyrrolidines.
Scheme 3: Synthesis of a hexacyclic compound via an organocatalyzed enantioselective polyene cyclization.
Scheme 4: Nickel-catalyzed asymmetric cross-coupling reactions.
Scheme 5: Chiral cobalt–porphyrin metalloradical-catalyzed radical cyclization reactions.
Scheme 6: Enantioselective radical chaperone catalysis.
Scheme 7: Enantioselective radical addition by decatungstate/iminium catalysis.
Scheme 8: An ene-reductase-catalyzed photoenzymatic enantioselective radical cyclization/enantioselective HAT...
Scheme 9: Photoenzymatic oxidative C(sp3)–C(sp3) coupling reactions between organoboron compounds and amino a...
Scheme 10: Electrochemical α-alkenylation reactions of 2-acylimidazoles catalyzed by a chiral-at-rhodium Lewis...
Scheme 11: Regio- and enantioselective electrochemical reactions of silyl polyenolates catalyzed by a chiral n...
Pathway economy in cyclization of 1,n-enynes
- Hezhen Han,
- Wenjie Mao,
- Bin Lin,
- Maosheng Cheng,
- Lu Yang and
- Yongxiang Liu
Beilstein J. Org. Chem. 2025, 21, 2260–2282, doi:10.3762/bjoc.21.173
- /AgSbF6 system, ultimately resulting in the formation of dihydrobenzo[a]fluorenes 123 via Friedel–Crafts alkylation (Scheme 25, path b). In 2018, the Shi research group developed an innovative intramolecular cyclization strategy using 1,6-enynes as substrates for the synthesis of 1,2-dihydroquinoline
- -catalyzed cyclization strategy for the synthesis of 1,2- and 2,3-fused quinazolinones, which was controlled by the angle strain of a key carbon atom in the substrate (Scheme 30) [43]. Experimental results showed intramolecular cyclization depended on the hybridization state of the carbon adjacent to
- intramolecular cyclization of 1,7-enynes. Brønsted acid-catalyzed cycloisomerizations of tryptamine ynamides. Catalyst-controlled cyclization of indolyl homopropargyl amides. Angle strain-dominated 6-endo-trig cyclization of propargyl vinyl ethers. Angle strain-controlled cycloisomerization of alkyn-tethered
Graphical Abstract
Scheme 1: Economical synthesis and pathway economy.
Scheme 2: Au(I)-catalyzed cascade cyclization paths of 1,5-enynes.
Scheme 3: Au(I)-catalyzed cyclization paths of 1,7-enynes.
Scheme 4: I2/TBHP-mediated radical cycloisomerization paths of 1,n-enyne.
Scheme 5: Au(I)-catalyzed cycloisomerization paths of 3-allyloxy-1,6-diynes.
Scheme 6: Pd(II)-catalyzed cycloisomerization paths of 2-alkynylbenzoate-cyclohexadienone.
Scheme 7: Stereoselective cyclization of 1,5-enynes.
Scheme 8: Substituent-controlled cycloisomerization of propargyl vinyl ethers.
Scheme 9: Au(I)-catalyzed pathway-controlled domino cyclization of 1,2-diphenylethynes.
Scheme 10: Au(I)-catalyzed tandem cyclo-isomerization of tryptamine-N-ethynylpropiolamide.
Scheme 11: Au(I)-catalyzed tunable cyclization of 1,6-cyclohexenylalkyne.
Scheme 12: Substituent-controlled 7-exo- and 8-endo-dig-selective cyclization of 2-propargylaminobiphenyl deri...
Scheme 13: BiCl3-catalyzed cycloisomerization of tryptamine-ynamide derivatives.
Scheme 14: Au(I)-mediated substituent-controlled cycloisomerization of 1,6-enynes.
Scheme 15: Ligand-controlled regioselective cyclization of 1,6-enynes.
Scheme 16: Ligand-dependent cycloisomerization of 1,7-enyne esters.
Scheme 17: Ligand-controlled cycloisomerization of 1,5-enynes.
Scheme 18: Ligand-controlled cyclization strategy of alkynylamide tethered alkylidenecyclopropanes.
Scheme 19: Ag(I)-mediated pathway-controlled cycloisomerization of tryptamine-ynamides.
Scheme 20: Gold-catalyzed cycloisomerization of indoles with alkynes.
Scheme 21: Catalyst-dependent cycloisomerization of dienol silyl ethers.
Scheme 22: Cycloisomerization of aromatic enynes governed by catalyst.
Scheme 23: Catalyst-dependent 1,2-migration in cyclization of 1-(indol-2-yl)-3-alkyn-1-ols.
Scheme 24: Gold-catalyzed cycloisomerization of N-propargyl-N-vinyl sulfonamides.
Scheme 25: Gold(I)-mediated enantioselective cycloisomerizations of ortho-(alkynyl)styrenes.
Scheme 26: Catalyst-controlled intramolecular cyclization of 1,7-enynes.
Scheme 27: Brønsted acid-catalyzed cycloisomerizations of tryptamine ynamides.
Scheme 28: Catalyst-controlled cyclization of indolyl homopropargyl amides.
Scheme 29: Angle strain-dominated 6-endo-trig cyclization of propargyl vinyl ethers.
Scheme 30: Angle strain-controlled cycloisomerization of alkyn-tethered indoles.
Scheme 31: Geometrical isomeration-dependent cycloisomerization of 1,3-dien-5-ynes.
Scheme 32: Temperature-controlled cyclization of 1,7-enynes.
Scheme 33: Cycloisomerizations of n-(o-ethynylaryl)acrylamides through temperature modulation.
Scheme 34: Temperature-controlled boracyclization of biphenyl-embedded 1,3,5-trien-7-ynes.
Synthesis of triazolo- and tetrazolo-fused 1,4-benzodiazepines via one-pot Ugi–azide and Cu-free click reactions
- Xiaoming Ma,
- Zijie Gao,
- Jiawei Niu,
- Wentao Shao,
- Shenghu Yan,
- Sai Zhang and
- Wei Zhang
Beilstein J. Org. Chem. 2025, 21, 2202–2210, doi:10.3762/bjoc.21.167
- . After evaporation of the solvent MeOH, the residue was redissolved in 2 mL of MeCN and heated at 130 °C for 2 h in a sealed vial to give product 7a in 90% yield after purification via Cu-free intramolecular click reaction (Scheme 3C) [46]. This Cu-free intramolecular cyclization provides key practical
Graphical Abstract
Figure 1: Some bioactive molecules bearing triazole, tetrazole, and 1,4-benzodiazepin rings.
Scheme 1: Ugi–azide reaction for the synthesis of 1,5-DS-T-containing heterocycles.
Scheme 2: Proposed Ugi–azide-initiated synthesis of polyheterocyclic scaffolds 7 and 8.
Scheme 3: 4-CR vs stepwise Ugi–azide reactions for the synthesis of 7a.
Scheme 4: Synthesis of benzodiazepines 7a–k. Reaction conditions: 1) 0.2 mmol each of 2-azidobenzaldehyde (1a...
Scheme 5: Synthesis of polycyclic compound 8a.
Scheme 6: Synthesis of product analogs 8. Reaction conditions: 1) 0.2 mmol each of 2-azidobenzaldehyde (1a) a...
Scheme 7: Control reactions to trap the Ugi–azide adduct.
Figure 2: 1H NMR spectra of compounds 6a (red) and 8a (blue).
Scheme 8: Gram-scale one-pot synthesis of 8a.
Electrochemical cyclization of alkynes to construct five-membered nitrogen-heterocyclic rings
- Lifen Peng,
- Ting Wang,
- Zhiwen Yuan,
- Bin Li,
- Zilong Tang,
- Xirong Liu,
- Hui Li,
- Guofang Jiang,
- Chunling Zeng,
- Henry N. C. Wong and
- Xiao-Shui Peng
Beilstein J. Org. Chem. 2025, 21, 2173–2201, doi:10.3762/bjoc.21.166
- radical cation G [232]. The following intramolecular cyclization/anode oxidation produced intermediate I that was then deprotonated to yield the target 33a. Compared to the previous reported methods [233][234][235][236][237][238][239][240][241][242][243][244][245][246][247][248][249][250][251][252][253
- experiments and previous works [260][261][262][263][264][265], a proposed mechanism was also presented. Initially, I− was oxidized to I• at the anode. A vinyl radical intermediate A was produced through reaction of I• with 39a. The following intramolecular cyclization formed the species B, which was oxidized
- electricity as a sustainable and green oxidant, noble metal catalyst (Rh) was required to achieve reasonable yields. An electrochemical synthesis of imidazoles through tandem Michael addition/azidation/intramolecular cyclization of alkynes, amines and azides was realized by Chen in 2022 (Scheme 17) [267
Graphical Abstract
Figure 1: Natural products and functional molecules possessing five-membered rings.
Scheme 1: Electrochemical intramolecular coupling of ureas to form indoles.
Scheme 2: Electrochemical dehydrogenative annulation of alkynes with anilines.
Scheme 3: Electrochemical annulations of o-arylalkynylanilines.
Scheme 4: Electrochemical cyclization of 2-ethynylanilines.
Scheme 5: Electrochemical selenocyclization of diselenides and 2-ethynylanilines.
Scheme 6: Electrochemical cascade approach towards 3-selenylindoles.
Scheme 7: Electrochemical C–H indolization.
Scheme 8: Electrochemical annulation of benzamides and terminal alkynes.
Scheme 9: Electrochemical synthesis of isoindolinone by 5-exo-dig aza-cyclization.
Scheme 10: Electrochemical reductive cascade annulation of o-alkynylbenzamide.
Scheme 11: Electrochemical intramolecular 1,2-amino oxygenation of alkyne.
Scheme 12: Electrochemical multicomponent reaction of nitrile, (thio)xanthene, terminal alkyne and water.
Scheme 13: Electrochemical aminotrifluoromethylation/cyclization of alkynes.
Scheme 14: Electrochemical cyclization of o-nitrophenylacetylene.
Scheme 15: Electrochemical annulation of alkynyl enaminones.
Scheme 16: Electrochemical annulation of alkyne and enamide.
Scheme 17: Electrochemical tandem Michael addition/azidation/cyclization.
Scheme 18: Electrochemical [3 + 2] cyclization of heteroarylamines.
Scheme 19: Electrochemical CuAAC to access 1,2,3-triazole.
α-Ketoglutaric acid in Ugi reactions and Ugi/aza-Wittig tandem reactions
- Vladyslav O. Honcharov,
- Yana I. Sakhno,
- Olena H. Shvets,
- Vyacheslav E. Saraev,
- Svitlana V. Shishkina,
- Tetyana V. Shcherbakova and
- Valentyn A. Chebanov
Beilstein J. Org. Chem. 2025, 21, 2021–2029, doi:10.3762/bjoc.21.157
- in 33–93% yields (Scheme 3; Table 3). According to the literature [31][53], this reaction proceeds through the formation of an iminophosphorane intermediate (Scheme 3), the product of a Staudinger reaction, which, however, was not isolated because it easily undergoes intramolecular cyclization on a
Graphical Abstract
Figure 1: Some biologically active quinoxalinone derivatives.
Scheme 1: Known multicomponent reactions of KGA.
Scheme 2: Ugi reaction involving KGA.
Scheme 3: Tandem Ugi/aza-Wittig combination involving KGA.
Figure 2: Molecular structure of 3-(4-(2-(tert-butylamino)-1-(4-methoxyphenyl)-2-oxoethyl)-5,7-dimethyl-3-oxo...
Aryl iodane-induced cascade arylation–1,2-silyl shift–heterocyclization of propargylsilanes under copper catalysis
- Rasma Kroņkalne,
- Rūdolfs Beļaunieks,
- Armands Sebris,
- Anatoly Mishnev and
- Māris Turks
Beilstein J. Org. Chem. 2025, 21, 1984–1994, doi:10.3762/bjoc.21.154
- likely formed via the allylic cation intermediate Int-1 (Scheme 2), from where on two competing mechanistic pathways are possible. Deprotonation of the β-H and reductive elimination affords diene 10. Alternatively, an intramolecular cyclization leads to silylindenes 11. We were interested to see whether
Graphical Abstract
Scheme 1: Alkyne arylation with diaryl-λ3-iodanes in the context of 1,2-silyl shift and potential cyclization....
Scheme 2: Competing mechanistic pathways for diene 10 and indene 11 formation.
Scheme 3: Reaction scope for the synthesis of arylated tetrahydrofurans 8. Conditions: All reactions were per...
Scheme 4: Synthesis of lactone and pyrrolidine derivatives. Conditions: ac7e = 0.1 mmol/mL. bReaction conditi...
Scheme 5: Proposed arylation–heterocyclization mechanism for internal nucleophile-containing silanes 7.
Scheme 6: Arylation of C5-chain containing acylamides 16a–c. aThe reaction was performed under modified condi...
Enantioselective desymmetrization strategy of prochiral 1,3-diols in natural product synthesis
- Lihua Wei,
- Rui Yang,
- Zhifeng Shi and
- Zhiqiang Ma
Beilstein J. Org. Chem. 2025, 21, 1932–1963, doi:10.3762/bjoc.21.151
- intramolecular cyclization of 16 generated benzofuran 17 in 83% yield. After protecting the phenolic hydroxy group of 17, cross-metathesis (CM) with allylic alcohol 18 catalyzed by 13 furnished intermediate 19. Desilylation of 19 produced heliannuol G (20) and heliannuol H (21), with the structure of 21
- . Epoxidation of 131 followed by methylation generated epoxide 132. Construction of the lactone moiety commenced with the oxidative cleavage of the double bond, and the resulting carboxylic acid underwent intramolecular cyclization in the presence of BF3·Et2O to give lactone 133. Subsequent hydride reduction
- synthesis of (−)-12-methoxy-Nb-methylvoachalotine (Scheme 31a) [78], (+)-12-methoxy-Na-methylvellosimine (252) was first prepared in ten steps from aniline 251, including a Larock indolization, Pictet–Spengler reaction, and Pd-catalyzed intramolecular cyclization. Tollens reaction of 252 gave diol 253
Graphical Abstract
Scheme 1: General mechanism of a lipase-catalyzed esterification.
Scheme 2: Shishido’s synthesis of (−)-xanthorrhizol (4) and (+)-heliannuol D (8).
Scheme 3: Shishido’s synthesis of a) (−)-heliannuol A (15) and b) heliannuol G (20) and heliannuol H (21).
Scheme 4: Deska’s synthesis of hyperione A (30) and ent-hyperione B (31).
Scheme 5: Huang’s synthesis of (+)-brazilin (37).
Scheme 6: Shishido’s synthesis of (−)-heliannuol D (42) and (+)-heliannuol A (43).
Scheme 7: Chênevert’s synthesis of (S)-α-tocotrienol (49).
Scheme 8: Kita’s synthesis of monoester 53.
Scheme 9: Kita’s synthesis of fredericamycin A (60).
Scheme 10: Takabe’s synthesis of (E)-3,7-dimethyl-2-octene-1,8-diol (64).
Scheme 11: Takabe’s synthesis of (18S)-variabilin (70).
Scheme 12: Kawasaki’s synthesis of (S)-Rosaphen (74) and (R)-Rosaphen (75).
Scheme 13: Tokuyama’s synthesis of a) (−)-petrosin (84) and b) (+)-petrosin (86).
Scheme 14: Fukuyama’s synthesis of leustroducsin B (96).
Scheme 15: Nanda’s synthesis of a) fragment 100, b) fragment 106 and c) (−)-rasfonin (109).
Scheme 16: Davies’ synthesis of (+)-pilocarpine (115) and (+)-isopilocarpine (116).
Scheme 17: Ōmura’s synthesis of salinosporamide A (125).
Scheme 18: Kang’s synthesis of ʟ-cladinose (124) and its derivative.
Scheme 19: Kang’s preparation of fragment 139.
Scheme 20: Kang’s synthesis of azithromycin (149).
Scheme 21: Kang’s synthesis of (−)-dysiherbaine (156).
Scheme 22: Kang’s synthesis of (−)-kaitocephalin (166).
Scheme 23: Kang’s synthesis of laidlomycin (180).
Scheme 24: Snyder’s synthesis of arboridinine (190).
Scheme 25: Ma’s synthesis of (+)-alstrostine G (203).
Scheme 26: Trost’s synthesis of (−)-18-epi-peloruside A (215).
Scheme 27: Lindel’s synthesis of (–)-dihydroraputindole (223).
Scheme 28: Iwata’s synthesis of a) (−)-talaromycin B (232) and b) (+)-talaromycin A (235).
Scheme 29: Cook’s synthesis of a) (−)-vincamajinine (240) and b) (−)-11-methoxy-17-epivincamajine (245).
Scheme 30: Cook’s synthesis of (+)-dehydrovoachalotine (249) and voachalotine (250).
Scheme 31: Cook’s synthesis of a) (−)-12-methoxy-Nb-methylvoachalotine (257) and b) (+)-polyneuridine, macusin...
Scheme 32: Trauner’s synthesis of stephadiamine (273).
Scheme 33: Garg’s synthesis of (–)-ψ-akuammigine (285).
Scheme 34: Ding’s synthesis of (+)-18-benzoyldavisinol (293) and (+)-davisinol (294).
Fe-catalyzed efficient synthesis of 2,4- and 4-substituted quinolines via C(sp2)–C(sp2) bond scission of styrenes
- Prafull A. Jagtap,
- Manish M. Petkar,
- Vaishnavi R. Sawant and
- Bhalchandra M. Bhanage
Beilstein J. Org. Chem. 2025, 21, 1799–1807, doi:10.3762/bjoc.21.142
- cycloaddition, tandem annulation, intramolecular cyclization, and cross-coupling reactions are commonly employed under thermal conditions, utilizing metal catalysts based on Pd, Ru, Au, Cu, and Fe to access a wide array of substituted quinoline frameworks [29][30][31][32][33][34][35][36][37][38]. Conversely, in
Graphical Abstract
Figure 1: Representative examples of bioactive quinolines.
Scheme 1: C(sp2)–C(sp2) bond-cleavage strategies for quinoline synthesis.
Scheme 2: Substrate scope of various arylamines and styrenes.
Scheme 3: Scale-up studies for the synthesis of antifungal agents.
Scheme 4: Mechanistic investigations.
Scheme 5: Plausible reaction mechanism.
Catalytic asymmetric reactions of isocyanides for constructing non-central chirality
- Jia-Yu Liao
Beilstein J. Org. Chem. 2025, 21, 1648–1660, doi:10.3762/bjoc.21.129
- condensation between 27 and the aldehyde afforded INT-A, which was activated by the CPA catalyst through hydrogen bonding interaction. The nucleophilic addition of isocyanide to Int-A produced INT-B bearing a stereogenic center. Subsequently, INT-B underwent intramolecular cyclization to generate axially
Graphical Abstract
Figure 1: a) Common types of chirality. b) Representative functional molecules bearing non-central chirality.
Scheme 1: Construction of planar chirality.
Scheme 2: Construction of axial chirality.
Scheme 3: Construction of inherent chirality.
Scheme 4: Construction of helical chirality.
Scheme 5: CPA-catalyzed enantioselective Groebke–Blackburn–Bienaymé reaction.
Scheme 6: Construction of axially chiral 3-arylpyrroles via de novo pyrrole formation.
Scheme 7: Synthesis of atropoisomeric 3-arylpyrroles via central-to-axial chirality transfer.
Scheme 8: Dynamic kinetic resolution of bridged biaryls with α-acidic isocyanides.
Scheme 9: Desymmetrization of prochiral compounds with α-acidic isocyanides.
Synthesis of optically active folded cyclic dimers and trimers
- Ena Kumamoto,
- Kana Ogawa,
- Kazunori Okamoto and
- Yasuhiro Morisaki
Beilstein J. Org. Chem. 2025, 21, 1603–1612, doi:10.3762/bjoc.21.124
- ]paracyclophanes via Wurtz-type intramolecular cyclization [3]. [2.2]Paracyclophane has a molecular structure in which two benzene rings are stacked face-to-face with ethylene chains at the para positions. Various studies have been conducted on their reactivities and physical properties derived from their unique
Graphical Abstract
Scheme 1: Synthesis of cyclic dimer (Sp)-6 and trimer (Sp)-7.
Figure 1: UV–vis and PL spectra of (Sp)-6 and (Sp)-7 in CHCl3 (1.0 × 10−5 M). Excitation wavelength 370 nm an...
Figure 2: (A) UV, CD, PL, and CPL spectra of (Sp)- and (Rp)-6 in CHCl3 (1.0 × 10−5 M). (B) UV, CD, PL, and CP...
Figure 3: (A) CD spectrum of (Sp)-6 in CHCl3 (1.0 × 10−5 M), and the plot of the calculated rotatory strength...
Figure 4: Molecular orbitals and simulated CPL profiles in the S1 states of (A) (Sp)-6 and (B) (Sp)-7 (TD-MN1...
Recent advances and future challenges in the bottom-up synthesis of azulene-embedded nanographenes
- Bartłomiej Pigulski
Beilstein J. Org. Chem. 2025, 21, 1272–1305, doi:10.3762/bjoc.21.99
- [52]. With the appropriate choice of substrates, this approach can also be used for the synthesis of π-extended azulenes. For example, Tobe and co-workers conducted the intramolecular cyclization of 1,4,5,8-tetrakis(mesitylethynyl)naphthalene 50 using I2 in CH2Cl2 (Scheme 8) [53]. In the reaction
Graphical Abstract
Figure 1: a) Stone–Wales (red) and azulene (blue) defects in graphene; b) azulene and its selected resonance ...
Figure 2: Examples of azulene-embedded 2D allotropic forms of carbon: a) phagraphene and b) TPH-graphene.
Scheme 1: Synthesis of non-alternant isomers of pyrene (2 and 6) using dehydrogenation.
Scheme 2: Synthesis of non-alternant isomer 9 of benzo[a]pyrene and 14 of benzo[a]perylene using dehydrogenat...
Scheme 3: Synthesis of azulene-embedded isomers of benzo[a]pyrene (18 and 22) inspired by Ziegler–Hafner azul...
Figure 3: General strategies leading to azulene-embedded nanographenes: a) construction of azulene moiety in ...
Scheme 4: Synthesis of biradical PAHs possessing significant biradical character using oxidation of partially...
Scheme 5: Synthesis of dicyclohepta[ijkl,uvwx]rubicene (29) and its further modifications.
Scheme 6: Synthesis of warped PAHs with one embedded azulene subunit using Scholl-type oxidation.
Scheme 7: Synthesis of warped PAHs with two embedded azulene subunits using Scholl oxidation.
Scheme 8: Synthesis of azulene-embedded PAHs using [3 + 2] annulation accompanied by ring expansion.
Scheme 9: Synthesis of azulene-embedded isomers of linear acenes using [3 + 2] annulation accompanied by ring...
Scheme 10: Synthesis of azulene-embedded PAHs using intramolecular C–H arylation.
Scheme 11: Synthesis of azulene-embedded isomers of acenes using intramolecular C–H arylation.
Scheme 12: Synthesis of azulene-embedded PAHs using intramolecular condensations.
Scheme 13: Synthesis of azulene-embedded PAH 89 using palladium-catalysed [5 + 2] annulation.
Scheme 14: Synthesis of azulene-embedded PAHs using oxidation of substituents around the azulene core.
Scheme 15: Synthesis of azulene-embedded PAHs using the oxidation of reactive positions 1 and 3 of azulene sub...
Scheme 16: Synthesis of azulene-embedded PAHs using intramolecular C–H arylation.
Scheme 17: Synthesis of an azulene-embedded isomer of terylenebisimide using tandem Suzuki coupling and C–H ar...
Scheme 18: Synthesis of azulene embedded PAHs using a bismuth-catalyzed cyclization of alkenes.
Scheme 19: Synthesis of azulene-embedded nanographenes using intramolecular cyclization of alkynes.
Scheme 20: Synthesis of azulene-embedded graphene nanoribbons and azulene-embedded helicenes using annulation ...
Scheme 21: Synthesis of azulene-fused acenes.
Scheme 22: Synthesis of non-alternant isomer of perylene 172 using Yamamoto-type homocoupling.
Scheme 23: Synthesis of N- and BN-nanographenes with embedded azulene unit(s).
Scheme 24: On-surface synthesis of azulene-embedded nanographenes from benzenoid precursors via dehydrogenatio...
Scheme 25: On-surface synthesis of azulene-embedded nanographenes from benzenoid precursors.
Scheme 26: On-surface synthesis of azulene-embedded nanoribbons.
Recent advances in oxidative radical difunctionalization of N-arylacrylamides enabled by carbon radical reagents
- Jiangfei Chen,
- Yi-Lin Qu,
- Ming Yuan,
- Xiang-Mei Wu,
- Heng-Pei Jiang,
- Ying Fu and
- Shengrong Guo
Beilstein J. Org. Chem. 2025, 21, 1207–1271, doi:10.3762/bjoc.21.98
- intramolecular cyclization to form a benzene ring radical intermediate D. Finally, hydrogen abstraction from the radical intermediate by Fe3+(OH) leads to the formation of oxindole compounds 5. A similar reaction was reported by Liang’s group in the same year, as shown in Scheme 4. The study introduced a metal
- subsequently adds to the activated alkene of N-arylacrylamide, followed by intramolecular cyclization, ultimately leading to the formation of the hydroxy-containing oxindole via the loss of a hydrogen radical. In 2016, Han and colleagues developed a novel methodology in which TBHP served dual roles as both
- intermediate 12. Subsequent intramolecular cyclization and oxidative aromatization lead to the final isoxazoline-featured oxindole 9. In 2017, Li’s group reported an oxidative divergent bicyclization of 1,n-enynes through α-C(sp3)–H functionalization of alkyl nitriles using a Sc(OTf)3 and Ag2O system (Scheme 7
Graphical Abstract
Scheme 1: DTBP-mediated oxidative alkylarylation of activated alkenes.
Scheme 2: Iron-catalyzed oxidative 1,2-alkylarylation.
Scheme 3: Possible mechanism for the iron-catalyzed oxidative 1,2-alkylation of activated alkenes.
Scheme 4: A metal-free strategy for synthesizing 3,3-disubstituted oxindoles.
Scheme 5: Iminoxyl radical-promoted cascade oxyalkylation/alkylarylation of alkenes.
Scheme 6: Proposed mechanism for the iminoxyl radical-promoted cascade oxyalkylation/alkylarylation of alkene...
Scheme 7: Bicyclization of 1,n-enynes with alkyl nitriles.
Scheme 8: Possible reaction mechanism for the bicyclization of 1,n-enynes with alkyl nitriles.
Scheme 9: Radical cyclization of N-arylacrylamides with isocyanides.
Scheme 10: Plausible mechanism for the radical cyclization of N-arylacrylamides with isocyanides.
Scheme 11: Electrochemical dehydrogenative cyclization of 1,3-dicarbonyl compounds.
Scheme 12: Plausible mechanism for the dehydrogenative cyclization of 1,3-dicarbonyl compounds.
Scheme 13: Photocatalyzed cyclization of N-arylacrylamide and N,N-dimethylaniline.
Scheme 14: Proposed mechanism for the photocatalyzed cyclization of N-arylacrylamides and N,N-dimethylanilines....
Scheme 15: Electrochemical monofluoroalkylation cyclization of N-arylacrylamides with dimethyl 2-fluoromalonat...
Scheme 16: Proposed mechanism for the electrochemical radical cyclization of N-arylacrylamides with dimethyl 2...
Scheme 17: Photoelectrocatalytic carbocyclization of unactivated alkenes using simple malonates.
Scheme 18: Plausible mechanism for the photoelectrocatalytic carbocyclization of unactivated alkenes with simp...
Scheme 19: Bromide-catalyzed electrochemical trifluoromethylation/cyclization of N-arylacrylamides.
Scheme 20: Proposed mechanism for the electrochemical trifluoromethylation/cyclization of N-arylacrylamides.
Scheme 21: Visible light-mediated trifluoromethylarylation of N-arylacrylamides.
Scheme 22: Plausible reaction mechanism for the visible light-mediated trifluoromethylarylation of N-arylacryl...
Scheme 23: Electrochemical difluoroethylation cyclization of N-arylacrylamides with sodium difluoroethylsulfin...
Scheme 24: Electrochemical difluoroethylation cyclization of N-methyacryloyl-N-alkylbenzamides with sodium dif...
Scheme 25: Photoredox-catalyzed radical aryldifluoromethylation of N-arylacrylamides with S-(difluoromethyl)su...
Scheme 26: Proposed mechanism for the photoredox-catalyzed radical aryldifluoromethylation of N-arylacrylamide...
Scheme 27: Visible-light-induced domino difluoroalkylation/cyclization of N-cyanamide alkenes.
Scheme 28: Proposed mechanism of photoredox-catalyzed radical domino difluoroalkylation/cyclization of N-cyana...
Scheme 29: Palladium-catalyzed oxidative difunctionalization of alkenes.
Scheme 30: Two possible mechanisms of palladium-catalyzed oxidative difunctionalization.
Scheme 31: Silver-catalyzed oxidative 1,2-alkyletherification of unactivated alkenes with α-bromoalkylcarbonyl...
Scheme 32: Photochemical radical cascade cyclization of dienes.
Scheme 33: Proposed mechanism for the photochemical radical cascade 6-endo cyclization of dienes with α-carbon...
Scheme 34: Photocatalyzed radical coupling/cyclization of N-arylacrylamides and.
Scheme 35: Photocatalyzed radical-type couplings/cyclization of N-arylacrylamides with sulfoxonium ylides.
Scheme 36: Possible mechanism of visible-light-induced radical-type couplings/cyclization of N-arylacrylamides...
Scheme 37: Visible-light-promoted difluoroalkylated oxindoles systhesis via EDA complexes.
Scheme 38: Possible mechanism for the visible-light-promoted radical cyclization of N-arylacrylamides with bro...
Scheme 39: A dicumyl peroxide-initiated radical cascade reaction of N-arylacrylamide with DCM.
Scheme 40: Possible mechanism of radical cyclization of N-arylacrylamides with DCM.
Scheme 41: An AIBN-mediated radical cascade reaction of N-arylacrylamides with perfluoroalkyl iodides.
Scheme 42: Possible mechanism for the reaction with perfluoroalkyl iodides.
Scheme 43: Photoinduced palladium-catalyzed radical annulation of N-arylacrylamides with alkyl halides.
Scheme 44: Radical alkylation/cyclization of N-Alkyl-N-methacryloylbenzamides with alkyl halides.
Scheme 45: Possible mechanism for the alkylation/cyclization with unactivated alkyl chlorides.
Scheme 46: Visible-light-driven palladium-catalyzed radical cascade cyclization of N-arylacrylamides with unac...
Scheme 47: NHC-catalyzed radical cascade cyclization of N-arylacrylamides with alkyl bromides.
Scheme 48: Possible mechanism of NHC-catalyzed radical cascade cyclization.
Scheme 49: Electrochemically mediated radical cyclization reaction of N-arylacrylamides with freon-type methan...
Scheme 50: Proposed mechanistic pathway of electrochemically induced radical cyclization reaction.
Scheme 51: Redox-neutral photoinduced radical cascade cylization of N-arylacrylamides with unactivated alkyl c...
Scheme 52: Proposed mechanistic hypothesis of redox-neutral radical cascade cyclization.
Scheme 53: Thiol-mediated photochemical radical cascade cylization of N-arylacrylamides with aryl halides.
Scheme 54: Proposed possible mechanism of thiol-mediated photochemical radical cascade cyclization.
Scheme 55: Visible-light-induced radical cascade bromocyclization of N-arylacrylamides with NBS.
Scheme 56: Possible mechanism of visible-light-induced radical cascade cyclization.
Scheme 57: Decarboxylation/radical C–H functionalization by visible-light photoredox catalysis.
Scheme 58: Plausible mechanism of visible-light photoredox-catalyzed radical cascade cyclization.
Scheme 59: Visible-light-promoted tandem radical cyclization of N-arylacrylamides with N-(acyloxy)phthalimides....
Scheme 60: Plausible mechanism for the tandem radical cyclization reaction.
Scheme 61: Visible-light-induced aerobic radical cascade alkylation/cyclization of N-arylacrylamides with alde...
Scheme 62: Plausible mechanism for the aerobic radical alkylarylation of electron-deficient amides.
Scheme 63: Oxidative decarbonylative [3 + 2]/[5 + 2] annulation of N-arylacrylamide with vinyl acids.
Scheme 64: Plausible mechanism for the decarboxylative (3 + 2)/(5 + 2) annulation between N-arylacrylamides an...
Scheme 65: Rhenium-catalyzed alkylarylation of alkenes with PhI(O2CR)2.
Scheme 66: Plausible mechanism for the rhenium-catalyzed decarboxylative annulation of N-arylacrylamides with ...
Scheme 67: Visible-light-induced one-pot tandem reaction of N-arylacrylamides.
Scheme 68: Plausible mechanism for the visible-light-initiated tandem synthesis of difluoromethylated oxindole...
Scheme 69: Copper-catalyzed redox-neutral cyanoalkylarylation of activated alkenes with cyclobutanone oxime es...
Scheme 70: Plausible mechanism for the copper-catalyzed cyanoalkylarylation of activated alkenes.
Scheme 71: Photoinduced alkyl/aryl radical cascade for the synthesis of quaternary CF3-attached oxindoles.
Scheme 72: Plausible photoinduced electron-transfer (PET) mechanism.
Scheme 73: Photoinduced cerium-mediated decarboxylative alkylation cascade cyclization.
Scheme 74: Plausible reaction mechanism for the decarboxylative radical-cascade alkylation/cyclization.
Scheme 75: Metal-free oxidative tandem coupling of activated alkenes.
Scheme 76: Control experiments and possible mechanism for 1,2-carbonylarylation of alkenes with carbonyl C(sp2...
Scheme 77: Silver-catalyzed acyl-arylation of activated alkenes with α-oxocarboxylic acids.
Scheme 78: Proposed mechanism for the decarboxylative acylarylation of acrylamides.
Scheme 79: Visible-light-mediated tandem acylarylation of olefines with carboxylic acids.
Scheme 80: Proposed mechanism for the radical cascade cyclization with acyl radical via visible-light photored...
Scheme 81: Erythrosine B-catalyzed visible-light photoredox arylation-cyclization of N-arylacrylamides with ar...
Scheme 82: Electrochemical cobalt-catalyzed radical cyclization of N-arylacrylamides with arylhydrazines or po...
Scheme 83: Proposed mechanism of radical cascade cyclization via electrochemical cobalt catalysis.
Scheme 84: Copper-catalyzed oxidative tandem carbamoylation/cyclization of N-arylacrylamides with hydrazinecar...
Scheme 85: Proposed reaction mechanism for the radical cascade cyclization by copper catalysis.
Scheme 86: Visible-light-driven radical cascade cyclization reaction of N-arylacrylamides with α-keto acids.
Scheme 87: Proposed mechanism of visible-light-driven cascade cyclization reaction.
Scheme 88: Peroxide-induced radical carbonylation of N-(2-methylallyl)benzamides with methyl formate.
Scheme 89: Proposed cyclization mechanism of peroxide-induced radical carbonylation with N-(2-methylallyl)benz...
Scheme 90: Persulfate promoted carbamoylation of N-arylacrylamides and N-arylcinnamamides.
Scheme 91: Proposed mechanism for the persulfate promoted radical cascade cyclization reaction of N-arylacryla...
Scheme 92: Photocatalyzed carboacylation with N-arylpropiolamides/N-alkyl acrylamides.
Scheme 93: Plausible mechanism for the photoinduced carboacylation of N-arylpropiolamides/N-alkyl acrylamides.
Scheme 94: Electrochemical Fe-catalyzed radical cyclization with N-arylacrylamides.
Scheme 95: Plausible mechanism for the electrochemical Fe-catalysed radical cyclization of N-phenylacrylamide.
Scheme 96: Substrate scope of the selective functionalization of various α-ketoalkylsilyl peroxides with metha...
Scheme 97: Proposed reaction mechanism for the Fe-catalyzed reaction of alkylsilyl peroxides with methacrylami...
Scheme 98: EDA-complex mediated C(sp2)–C(sp3) cross-coupling of TTs and N-methyl-N-phenylmethacrylamides.
Scheme 99: Proposed mechanism for the synthesis of oxindoles via EDA complex.
Enhancing chemical synthesis planning: automated quantum mechanics-based regioselectivity prediction for C–H activation with directing groups
- Julius Seumer,
- Nicolai Ree and
- Jan H. Jensen
Beilstein J. Org. Chem. 2025, 21, 1171–1182, doi:10.3762/bjoc.21.94
- Chen et al. [4]. We are excluding cyclization reactions for which the regioselectivity is not only determined by the activation energy to form the palladacycle intermediate but also by which site is accessible for the intramolecular cyclization. Using the previously described workflow, we were able to
- with the experimentally observed reaction site in green and the predicted reaction site marked by a blue circle. For molecule 1, we can see in the original paper from Yeung et al. [26] that the reaction preceding the C–H activation is an intramolecular cyclization between the C atom marked in green and
- the C atom marked by a blue circle. This reaction was originally not labelled as a cyclization reaction, which is why we did not remove it from the dataset. Nevertheless, upon inspection, our QM workflow correctly predicts the reaction site(s) of the intramolecular cyclization as it predicts one of
Graphical Abstract
Figure 1: Overview of the predictive workflow: For the shown substrate on the left, three unique activation s...
Figure 2: Example of the output from running the SMARTS pattern approach introduced by Tomberg et al. [9] with t...
Figure 3: An example where our algorithm found a more specific SMARTS pattern match than highlighted in Tombe...
Figure 4: An example highlighting the difficulties in prioritizing the SMARTS patterns. All three patterns ma...
Figure 5: Example of a combination of C–H bond and DG that is discarded because of the angle constraint on th...
Figure 6: Example of combinations of C–H bonds and DGs that are considered identical because of symmetry of t...
Figure 7: Example of combinations of C–H bonds and DGs that are considered identical because of symmetry of t...
Figure 8: Example of combinations of C–H bonds and DGs that are considered identical because of resonance str...
Figure 9: A: Distribution of correct (green) and wrong (red) predictions for molecules with two to five poten...
Figure 10: Molecules with five potential reaction sites that are predicted wrong by the QM workflow. The exper...
Figure 11: Predictions of reaction sites within a 1 kcal·mol−1 threshold for ten molecules are marked with a b...
Figure 12: Substrate with six potential unique reaction sites for C–H functionalization. The experimentally de...
Recent advances in controllable/divergent synthesis
- Jilei Cao,
- Leiyang Bai and
- Xuefeng Jiang
Beilstein J. Org. Chem. 2025, 21, 890–914, doi:10.3762/bjoc.21.73
- undergoes intramolecular cyclization into a proximal C(sp2)–H bond (ΔG‡ = +19.7 kcal·mol−1) to form Int-46, which reacts with 4-MePhSH (ΔG‡ = +14.9 kcal·mol−1) to yield radical intermediate Int-47 and a thiyl radical (4-MePhS·). Sequential thiol-assisted hydrogen shifts produce Int-48, followed by
Graphical Abstract
Scheme 1: Ligand-controlled regiodivergent C1 insertion into arynes [19].
Scheme 2: Ligand effect in homogenous gold catalysis enabling regiodivergent π-bond-activated cyclization [20].
Scheme 3: Ligand-controlled palladium(II)-catalyzed regiodivergent carbonylation of alkynes [21].
Scheme 4: Catalyst-controlled annulations of strained cyclic allenes with π-allyl palladium complexes and pro...
Scheme 5: Ring expansion of benzosilacyclobutenes with alkynes [23].
Scheme 6: Photoinduced regiodivergent and enantioselective cross-coupling [24].
Scheme 7: Catalyst-controlled regiodivergent and enantioselective formal hydroamination of N,N-disubstituted ...
Scheme 8: Catalyst-tuned regio- and enantioselective C(sp3)–C(sp3) coupling [31].
Scheme 9: Catalyst-controlled annulations of bicyclo[1.1.0]butanes with vinyl azides [32].
Scheme 10: Solvent-driven reversible macrocycle-to-macrocycle interconversion [39].
Scheme 11: Unexpected solvent-dependent reactivity of cyclic diazo imides and mechanism [40].
Scheme 12: Palladium-catalyzed annulation of prochiral N-arylphosphonamides with aromatic iodides [41].
Scheme 13: Time-dependent enantiodivergent synthesis [42].
Scheme 14: Time-controlled palladium-catalyzed divergent synthesis of silacycles via C–H activation [43].
Scheme 15: Proposed mechanism for the time-controlled palladium-catalyzed divergent synthesis of silacycles [43].
Scheme 16: Metal-free temperature-controlled regiodivergent borylative cyclizations of enynes [45].
Scheme 17: Nickel-catalyzed switchable site-selective alkene hydroalkylation by temperature regulation [46].
Scheme 18: Copper-catalyzed decarboxylative amination/hydroamination sequence [48].
Scheme 19: Proposed mechanism of copper-catalyzed decarboxylative amination/hydroamination sequence [48].
Scheme 20: Enantioselective chemodivergent three-component radical tandem reactions [49].
Scheme 21: Substrate-controlled synthesis of indoles and 3H-indoles [52].
Scheme 22: Controlled mono- and double methylene insertions into nitrogen–boron bonds [53].
Scheme 23: Copper-catalyzed substrate-controlled carbonylative synthesis of α-keto amides and amides [54].
Scheme 24: Divergent sulfur(VI) fluoride exchange linkage of sulfonimidoyl fluorides and alkynes [55].
Scheme 25: Modular and divergent syntheses of protoberberine and protonitidine alkaloids [56].
Cu–Bpin-mediated dimerization of 4,4-dichloro-2-butenoic acid derivatives enables the synthesis of densely functionalized cyclopropanes
- Patricia Gómez-Roibás,
- Andrea Chaves-Pouso and
- Martín Fañanás-Mastral
Beilstein J. Org. Chem. 2025, 21, 877–883, doi:10.3762/bjoc.21.71
- mechanism for the Cu-catalyzed dimerization of 4,4-dichoro-2-butenoic acid derivatives. a) KOt-Bu-mediated intramolecular cyclization of 9. b) Direct formation of cyclopropane 20 from gem-dichloride 5 using KOt-Bu as base. Optimization studies. Synthesis of densely functionalized (2,2-dichlorovinyl
- )cyclopropanes by base-promoted intramolecular cyclization. Supporting Information Supporting Information File 2: Experimental procedures, characterization data and copies of NMR spectra. Funding Financial support from the AEI (PID2020-118237RB-I00), European Research Council (863914), Xunta de Galicia (ED431C
Graphical Abstract
Scheme 1: Chemodivergent reactivity observed in copper-catalyzed borylative couplings of allylic gem-dichlori...
Scheme 2: Cu-Bpin-mediated dimerization of 4,4-dichoro-2-butenoic acid derivatives.
Scheme 3: Control experiments.
Scheme 4: Proposed mechanism for the Cu-catalyzed dimerization of 4,4-dichoro-2-butenoic acid derivatives.
Scheme 5: a) KOt-Bu-mediated intramolecular cyclization of 9. b) Direct formation of cyclopropane 20 from gem...
Recent advances in the electrochemical synthesis of organophosphorus compounds
- Babak Kaboudin,
- Milad Behroozi,
- Sepideh Sadighi and
- Fatemeh Asgharzadeh
Beilstein J. Org. Chem. 2025, 21, 770–797, doi:10.3762/bjoc.21.61
- phenyl rings' ortho, meta, or para positions. This method proceeded via an anodic oxidation, followed by intramolecular cyclization (Scheme 32). The key role of anodic oxidation became evident when the annulation product
Graphical Abstract
Scheme 1: Electrosynthesis of phenanthridine phosphine oxides.
Scheme 2: Electrosynthesis of 1-aminoalkylphosphine oxides.
Scheme 3: Various electrochemical C–P coupling reactions.
Scheme 4: Electrochemical C–P coupling reaction of indolines.
Scheme 5: Electrochemical C–P coupling reaction of ferrocene.
Scheme 6: Electrochemical C–P coupling reaction of acridines with phosphites.
Scheme 7: Electrochemical C–P coupling reaction of alkenes.
Scheme 8: Electrochemical C–P coupling reaction of arenes in a flow system.
Scheme 9: Electrochemical C–P coupling reaction of heteroarenes.
Scheme 10: Electrochemical C–P coupling reaction of thiazoles.
Scheme 11: Electrochemical C–P coupling reaction of indole derivatives.
Scheme 12: Electrosynthesis of 1-amino phosphonates.
Scheme 13: Electrochemical C–P coupling reaction of aryl and vinyl bromides.
Scheme 14: Electrochemical C–P coupling reaction of phenylpyridine with dialkyl phosphonates in the presence o...
Scheme 15: Electrochemical P–C bond formation of amides.
Scheme 16: Electrochemical synthesis of α-hydroxy phosphine oxides.
Scheme 17: Electrochemical synthesis of π-conjugated phosphonium salts.
Scheme 18: Electrochemical phosphorylation of indoles.
Scheme 19: Electrochemical synthesis of phosphorylated propargyl alcohols.
Scheme 20: Electrochemical synthesis of phosphoramidates.
Scheme 21: Electrochemical reaction of carbazole with diphenylphosphine.
Scheme 22: Electrochemical P–N coupling of carbazole with phosphine oxides.
Scheme 23: Electrochemical P–N coupling of indoles with a trialkyl phosphite.
Scheme 24: Electrochemical synthesis of iminophosphoranes.
Scheme 25: Electrochemical P–O coupling of phenols with dialkyl phosphonate.
Scheme 26: Electrochemical P–O coupling of alcohols with diphenylphosphine.
Scheme 27: Electrochemical P–S coupling of thiols with dialkylphosphines.
Scheme 28: Electrochemical thiophosphorylation of indolizines.
Scheme 29: Electrosynthesis of S-heteroaryl phosphorothioates.
Scheme 30: Electrochemical phosphorylation reactions.
Scheme 31: Electrochemical P–Se formation.
Scheme 32: Electrochemical selenation/halogenation of alkynyl phosphonates.
Scheme 33: Electrochemical enantioselective aryl C–H bond activation.
Synthesis of HBC fluorophores with an electrophilic handle for covalent attachment to Pepper RNA
- Raphael Bereiter and
- Ronald Micura
Beilstein J. Org. Chem. 2025, 21, 727–735, doi:10.3762/bjoc.21.56
- was impractical for the HBC derivative with a C4-handle (N-(4-bromobutyl)-HBC) due to intramolecular cyclization with the amine. To prevent intramolecular cyclization, we considered the 4-bromobutyl HBC ether 11 as a potential candidate with a 4-atom spacer. Accordingly, 4-hydroxybenzaldehyde was
Graphical Abstract
Figure 1: Structure-guided approach for engineering the (non-covalent) fluorescent light-up aptamer Pepper in...
Scheme 1: Chemical structures of the HBC dye family [7]. Variations to HBC530 highlighted in red color. All dyes...
Scheme 2: Synthesis of bromoalkyl HBC derivatives 7, 8, and 9.
Scheme 3: Synthesis of the HBC ether derivative 11.
Figure 2: Pepper aptamer reacts with different HBC derivatives. Chemical structures of the HBC derivatives us...
Scheme 4: Derivatization of the HBC fluorophore 5 to generate handles with distinct electrophilic groups.
Scheme 5: Synthesis of mesylated HBC fluorophores 16, 17, and 18.
Scheme 6: Synthesis of the bifunctional HBC fluorophore 22. For an application of 22 (pulldown of circular Pe...
